Trying to use Curl tutorial when doing vector calculus

when I enter F:=VectorField(⟨y,-x,0⟩); it tells me unknown operator.

Regards

with(VectorCalculus);
SetCoordinates('cartesian'[x, y, z]);
                       cartesian[x, y, z]

F:=VectorField(⟨y,-x,0⟩);

Error, unknown operator
Typesetting:-mambiguous(FAssignVectorFieldApplyFunction(acirc

  Typesetting:-mambiguous(?, 

  Typesetting:-merror("unknown operator"))umlycommauminus0xcomma0

  acirc?copy))

I want to creat a two dimisional plot of a circle.   Every time I try it gives me a parabola.